You may remember that Pluto is now classed as something called a “Dwarf Planet”. As well as Pluto, there are four other dwarf planets in our Solar System: Ceres, Haumea, Makemake, and Eris. Plus, there may be a new member joining the family very soon – an object nicknamed ‘DeeDee’.
But what is a dwarf planet?
Dwarf planets are small bodies that orbit the Sun, like planets (whereas moons orbit around planets). They’re spherical in shape, like planets. In fact, the only difference between a dwarf planet and a normal planet is that dwarf planets haven’t “cleaned up” their neighbourhood, removing stray asteroids and other small bits of space debris.
So, does DeeDee tick all these boxes? We’re not sure yet.
DeeDee is almost 100 times further from the Sun than the Earth, and three times further than Pluto. It’s the second most distant object ever discovered in our Solar System (the most distant is the dwarf planet Eris).
At this tremendous distance, it takes DeeDee more than 1,100 years to complete one orbit of the Sun. It also makes it incredibly difficult to see DeeDee, never mind study it in detail.
But the ALMA telescope has managed to collect an exciting new image of DeeDee. Revealing the small world is roughly 600 kilometers across — about the same size as the UK. At this size, DeeDee is very likely ball-shaped (when an object has enough material, gravity pulls it into a neat spherical shape).
More observations are needed before we can make the final verdict on DeeDee, but whether it’s a dwarf planet or not, Pluto has a new friend in the outer Solar System!
Dwarf planets aren’t the only objects still hiding in our Solar System. Some scientists suspect that another planet, nicknamed ‘Planet 9’, is lurking on the edge of our Solar System!